So what exactly is a glaze?
A ceramic glaze is a glass covering that provides a protective finish for a clay object. Over simplified, it is a combination of raw materials that react to heat to produce a glass coating on ceramic pieces. Colored and textured glazes have minerals and additives that produce exciting colors and effects.
The unfired glaze may look dull, drab, uninteresting and a totally different color before it is subjected to the intense heat of the kiln, but during the firing process it transforms itself into a dazzling array of colors and surfaces. Glazes can make ceramics leak proof, easy to clean, beautiful and can provide the protective coating that brings underglaze colors to life.
Glaze is not a paint in the traditional manner, but rather a combination of highly reactive chemicals and raw materials. For this reason, mixing two or more glazes or varying the thickness of application will not always give dependable results. Mixing a blue and a red glaze does not produce a purple colored glaze. Sometimes mixing two matte glazes may produce a gloss and two dinnerware safe glazes when mixed may not yield a dinnerware safe glaze.
SHAKE OR STIR YOUR GLAZE OFTEN !
Never thin a glaze prior to vigorously shaking it, there may be more water trapped under the glaze than you realize. If a glaze should require thinning, use SMALL amounts of distilled water or Media. For brush application the product should be the consistency of ketchup, but it is always a good idea to read the label as some glazes are designed to be a little on the thick side. If the glaze is so thin that it runs out of the brush before you can apply it, additional coats may be needed to get the equivalent of one "flowing coat".
The better you treat your brushes, the better they will treat your glazes !
Clean and well maintained brushes will give you the best glaze results. Dried glaze stuck under and around the ferrule (the point where the hairs are connected to the handle) may come off the next time you use the brush causing small discolored spots to appear in the glaze. Likewise, keep an eye on the condition of the ferrule itself. Brush ferrules are typically plated in nickel and if the nickel flakes off into the glaze it can cause greenish spots to form.
Dampening the brush will help insure it is completely clean and will allow the brush to accept the glaze, making it easier for the glaze to flow onto the ware. Dip the brush into the glaze then press against the inside of the jar to spread the hairs and cause them to accept the glaze. Jiggle the brush up and down a few times to the ferrule in order to fully load the reservoir. The brush should look considerably larger and fluffier than it did before. Do not empty the brush by wiping the glaze out again on the rim of the jar.
The brush should always be well loaded and saturated so that the glaze flows onto the bisque with sufficient thickness. If too mush pressure is applied to the brush and bends the hairs, you will be removing more glaze than you are applying. Do not scrub with the brush or you may cause a thin spot in the glaze.
How do I know if I am applying enough glaze?
It is difficult to establish exactly what is meant by a "coat" of glaze. Three coats could translate to four coats for someone who is termed a light glazer, while some people may only require two flowing coats to achieve the right deposit of glaze. The thickness of a post card is about the recommended thickness for the proper coverage after applications.
Each coat of glaze should be allowed to completely dry before applying each successive coat. A glaze is dry when it feels dry, not necessarily when the shiny wet look is gone. If it is not dry, the brush may pick up the glaze rather than put it down.
Clear glazes require two coats only, unless lusters or fired metallics are to be used over them. When two coats of clear glaze have been applied and allowed to dry, it should not be cold to the touch nor should you be able to see through the glaze.
The information listed above is intended to be suggestions for glaze application. Over time you will develop your own glazing style and techniques that lend themselves to your work and help to express the finished idea you have in mind. Do not be afraid to experiment and remember keep good glaze notes !!!
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